JP2003050567A - Liquid crystal display module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a conventional liquid crystal display module requires large power consumption when writing display data in a liquid crystal display panel. SOLUTION: The liquid crystal display module is provided with: a liquid crystal display panel 21; a row direction driver LSI 23 and a column direction driver LSI 24 for writing display data in the liquid crystal display panel 21; and an SRAM area for a picture and a program memory area as holding means which are arranged in an empty area of a memory circuit in the row direction driver LSI 23 and hold the display data and the commands for writing the display data. The display data are written in the liquid crystal panel 21 by a MPU 25 on the basis of the above commands. Thus, the liquid crystal display module has an access frequency from the MPU 25 remarkably reduced by providing the liquid crystal display module with the SRAM area for the picture and the program memory area, and thus low power consumption can easily be realized.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display module for displaying an image.

[0002]

2. Description of the Related Art In recent years, it has been required to display more data in mobile phones in order to cope with applications such as sending and receiving mails and displaying wallpaper. In such a liquid crystal display module, an STN color type small liquid crystal display panel is increasingly used due to the demand for lower power consumption and higher image quality. This STN
The color type consumes less power than other types of liquid crystal display panels such as TFT and MIM, and is therefore mainly used in current mobile phones.

In order to reduce the power consumption of the STN color type liquid crystal display panel, the ST with front light is used.
The adoption of N color reflective type small liquid crystal display panels is increasing. Compared with the transflective type with a back light, this reflective type with a front light has a higher utilization efficiency of the brightness of the surrounding environment in the normal use state, so that the front light lighting time as a light source can be shortened. Therefore, it is possible to reduce power consumption.

In order to reduce the power consumption of the drive circuit of the STN color type liquid crystal display module, an electrically volatile memory (SRAM) for holding display data and a liquid crystal display controller for sequentially transferring display data are used. A microcomputer (M) that is controlled by being built in each driver LSI in the liquid crystal display module.
PU) and the frequency of the data transfer clock from the external frame buffer memory can be remarkably lowered, and therefore, it is adopted in almost all of the current STN liquid crystal display module system configurations for mobile phones.

The following is a command execution procedure for data transfer from the MPU when the SRAM holding the display data of the liquid crystal display module and the liquid crystal display controller for sequentially transferring the display data are incorporated in the driver LSI in the liquid crystal display module. Will be described.

FIG. 1 shows a command execution procedure in which the display data is sequentially written from the MPU to the liquid crystal display module by an individual command when data is transferred from the conventional MPU. In FIG. 1, 11 is a liquid crystal display panel. Reference numeral 12 is a power supply circuit that generates a voltage for driving the liquid crystal display panel 11. Reference numeral 13 is a row-direction drive driver LSI with a built-in SRAM for holding display data. Reference numeral 14 is a column-direction drive driver LSI with a built-in liquid crystal display controller that sequentially transfers display data.

Reference numeral 15 is an MPU for transmitting display data and write commands. Reference numeral 16 is a frame buffer memory for the MPU 15 for temporarily holding the display data for writing. Reference numeral 17 is a read-only memory (ROM) in which a program controlling a display routine for the liquid crystal display module is written.

Next, a command execution procedure for data transfer from the MPU 15 in the liquid crystal display module configured as described above will be described.

The following operations are executed in the order of the programs written in the ROM 17. First, in order to display an image on the liquid crystal display panel 11, a command for initializing the row-direction driving driver LSI 13 and the column-direction driving driver LSI 14 is read from the ROM 17 by the MPU 15, and the row-direction driving driver LSI 1 is read from the MPU 15.
3 and the column direction drive driver LSI 14. As a result, the SRAM in the row-direction drive driver LSI 13 is cleared and the display data input waits.

Next, control data such as a drive duty ratio according to the number of vertical and horizontal dots of the liquid crystal display panel 11 is read from the ROM 17 by the MPU 15, and MP
The controller in the column direction drive driver LSI 14 is set to operate by being sent from the U15 to the column direction drive driver LSI 14.

Next, specific display data is transferred from the frame buffer memory 16 to the SRAM in the row-direction driver LSI 13. In this case, the address counter of the SRAM incorporated in the row-direction driver LSI 13 is set to be automatically incremented in most cases, which reduces the burden of address calculation on the MPU 15 side. The liquid crystal display panel 11 is turned on by sending a display-on command from the MPU 15 after writing data in the SRAM incorporated in the row-direction driver LSI 13. Here, the case in which the controller is built in the column-direction drive driver LSI 14 has been described, but there is a case in which the controller is built in the row-direction drive driver LSI 13, and the command execution procedure for lighting is the same.

[0012]

However, in the above-mentioned conventional command execution procedure, the MPU 15 requires a similar command execution procedure every time data is transferred to the liquid crystal display panel 11, so that the MPU 15 transfers to the liquid crystal display module. However, there is a problem that power consumption increases due to frequent command writing.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a liquid crystal display module which suppresses an increase in power consumption by reducing the number of times commands are written from the MPU or CPU. It is a thing.

[0014]

To achieve this object, a first aspect of the present invention (corresponding to claim 1) is a liquid crystal display panel and a row-direction driver for writing display data to the liquid crystal display panel. And a column direction driver, and a holding unit for holding the display data and a command for writing the display data, and the display data is written in the liquid crystal display panel based on the command by the MPU or the CPU. It is a display module.

A second aspect of the present invention (corresponding to claim 2) is the liquid crystal display module according to the first aspect of the present invention, wherein the holding means is a volatile memory circuit.

The third aspect of the present invention (corresponding to claim 3) is the first aspect.
Alternatively, it is a mobile phone including at least the liquid crystal display module according to the second aspect of the present invention and the MPU or the CPU.

As described above, the liquid crystal display module of the present invention is provided with the holding means (for example, the memory circuit) for holding the data and the command from the MPU or CPU, so that the command frequently transferred from the MPU or CPU. MPU or C as a user-defined instruction such as a column
It has a configuration that can be executed from the PU.

According to this configuration, the command sequence executed by the MPU or CPU each time the display content is rewritten is set as one user-defined instruction in the holding means, so that when viewed from the MPU or CPU, Since the command is executed once, it is possible to significantly reduce power consumption.
The commands to be further defined are, of course, easily changeable by user setting.

Further, the holding means for holding the user-defined instruction can use the empty area of the SRAM built in the driver or can be expanded a little,
No new process technology is required.

As described above, according to this configuration, the user-defined command string written in the holding means such as the empty area of the memory circuit with built-in driver is set and executed as one instruction, so that the MPU or CPU It is possible to provide a liquid crystal display module that can easily realize low power consumption by significantly reducing the number of accesses.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG. FIG. 2 is a diagram illustrating a liquid crystal display module configured to write and execute a user-defined instruction in an empty area of the memory circuit with a built-in driver according to the embodiment of the present invention.

In FIG. 2, reference numeral 21 is a liquid crystal display panel. Reference numeral 22 is a power supply circuit that generates a voltage for driving the liquid crystal display panel 21. Reference numeral 23 is a row-direction drive driver LSI with a built-in SRAM for holding display data. 24
Is a column-direction drive driver LSI with a built-in liquid crystal display controller that sequentially transfers display data. Reference numeral 25 is an MPU that sends display data, a write command, and the like. Two
6 is an M for temporarily holding the display data for writing.
It is a frame buffer memory for the PU 25. Reference numeral 27 is a read-only memory (ROM) in which a program controlling a display routine for the liquid crystal display module is written.

Next, a procedure for writing and executing a user-defined command in the liquid crystal display module configured as described above will be described. The following operations are in ROM
The programs written in 27 are executed in order, but the difference from the conventional one is that when actually operating, the MPU 25
It is to be executed without going through. That is, the following command sequence is applied to the SRAM in the row-direction driver LSI 23.
All you have to do is write to the free space at and execute the new user-defined instruction.

First, the row-direction drive driver LSI 23 and the column-direction drive driver LSI 24 are initialized, the SRAM in the row-direction drive driver LSI 23 is cleared, and a command for securing a program memory area is written.
Next, control data such as a drive duty ratio according to the number of vertical and horizontal dots of the liquid crystal display panel 21 is written. Next, after writing specific display data to the frame buffer memory 26, the frame buffer memory 26 is accessed to write a command to transfer data to the SRAM, a start address to be transferred, and a data amount. Finally, write the display on command.

As described above, the head address of the user-defined command written in the program memory is accessed from the MPU 25 and executed, and thereafter, the MPU 2 is executed.
The display lighting command ends without access from 5.

For this program memory, it is easiest to use an unused area of the SRAM built in the row-direction driver LSI 23, but if there is not enough SRAM area, such as when using a plurality of user-defined commands. It is necessary to use an LSI with an expanded memory area. However, even in this case, there is no need to greatly improve the process technology during LSI manufacturing, so it is possible to easily introduce the existing process rules without improving them, contributing to the reduction of development costs and development spans. can do. In addition, since the user-defined command can be rewritten arbitrarily as a matter of course, there is a high degree of freedom in operating it.

As described above, in the liquid crystal display module of this embodiment, the number of accesses from the MPU 25 is written by writing a user-defined command sequence as a new command in the empty area of the memory circuit built in the driver 23 and executing it. By reducing the power consumption, it is possible to easily realize low power consumption.

In the above-described embodiment, the SRAM in the row-direction driver LSI 23 is used as an example of the holding means of the liquid crystal display module of the present invention. Further, the holding means may be a volatile memory circuit.

Further, the liquid crystal display module of the present invention, M
A mobile phone equipped with a PU or a CPU also belongs to the present invention.

[0030]

As is apparent from the above description, the present invention can provide a liquid crystal display module which suppresses an increase in power consumption by reducing the number of times of writing commands from the MPU or CPU. .

[Brief description of drawings]

FIG. 1 is a diagram for explaining a liquid crystal display module configured to sequentially write display data from the MPU to the liquid crystal display module by individual commands when data is transferred from the conventional MPU.

FIG. 2 is a diagram for explaining a liquid crystal display module configured to write and execute a user-defined instruction in an empty area of a memory circuit with a built-in driver according to an embodiment of the present invention.

[Explanation of symbols]

11, 21 Liquid crystal display panels 12, 22 Power supply circuits 13, 23 for generating a voltage for driving the liquid crystal display panels Row-direction drive driver LSIs 14, 24 with built-in SRAM for holding display data Liquid crystal display for sequentially transferring display data Column-direction drive driver LSI 15 and 25 with built-in controller for MPU 16 and 26 for sending display data and write command etc. MPU frame buffer memory 17 and 27 for temporarily holding display data for writing To liquid crystal display module Read-only memory (ROM) in which the program that controls the display routine is written

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 680 G09G 3/20 680S F term (reference) 2H093 NA10 NA80 NC13 NC28 NC50 ND32 ND39 ND42 NG20 5C006 AA02 AC01 AC21 AF11 BB12 BC11 BC16 BF08 BF15 EC05 FA47 5C080 AA10 BB05 DD26 FF08 FF09 JJ02 JJ07 KK07

Claims (3)

[Claims] 1. A liquid crystal display panel, a row-direction driver and a column-direction driver for writing display data to the liquid crystal display panel, and holding means for holding the display data and a command for writing the display data. A liquid crystal display module in which the display data is written in the liquid crystal display panel by an MPU or a CPU based on the command. 2. The liquid crystal display module according to claim 1, wherein the holding means is a volatile memory circuit. 3. A mobile phone comprising at least the liquid crystal display module according to claim 1 or 2 and the MPU or the CPU.